Compositions for combatting body odour are an important component of daily personal hygiene. They are supposed to ensure that perspiration formed during the course of the day due to various activities (moving the body, work, sport), and also during psychological stress, does not give rise to unpleasant body odour.
The multiple components of perspiration and the multiple causes of body odour development are matched by the multiple deodorizing substances in commercial deodorants. Substances which may be used as cosmetic deodorizing substances are odour absorbers, fragrances, ion exchangers with deodorizing activity, bacteriostatic agents, probiotic components as well as enzyme inhibitors. Put simply, body odour can be caused by the bacteria decomposition of the organic components of perspiration. In turn, some of the typical bacteria found in the natural microflora of human skin are responsible for bacterial decomposition, in particular gram-positive anaerobic cocci, for example staphylococci, such as Staphylococcus hominis, and corynebacteria. Because body odour arises because of bacterial activity, it can be inhibited particularly effectively using cosmetic agents (soaps, creams, powder, sticks, roll-ons, gels or sprays) which contain antimicrobially effective materials and perfume oil compositions.
Aerosol sprays, roll-ons and antiperspirant sticks have become well-established application forms for said compositions. Furthermore, deodorant in powder form (also as a compressed powder) or deodorant applied to a disposable substrate (such as a towel, pad or ball) are also known. A particularly pleasant form of application is known to the person skilled in the art as an antiperspirant stick or cream stick (soft solids). This should be understood to mean viscous compositions which have a creamy texture and which, before application, are pressed through one or more openings of a dispensing portion of an applicator.
Antiperspirant sticks are usually produced in a water-depleted or anhydrous manner. Anhydrous production is then particularly preferred over aqueous systems when a particularly high perspiration-inhibiting activity is desired, because particularly effective perspiration-inhibiting substances such as activated aluminium chlorohydrate are not stable in the long term in aqueous media.
In water-depleted, preferably anhydrously produced antiperspirants, producing a stable active composition and producing optimal application properties constitute a very particular challenge. Anhydrous antiperspirant sticks can, for example, be produced by suspending perspiration-inhibiting aluminium salts in a thickened oily phase. Sticks of this type, however, frequently have insufficient physical stability (synaeresis). This phenomenon can be countered by adding supplemental thickeners, but adding such thickeners results in an unwanted high stick hardness which then has disadvantageous effects on the payout properties of the stick.
In the light of this technical background, the technical problem was to provide an antiperspirant in stick form which has high physical stability in addition to outstanding cosmetic application properties.